Such a method is known from the publication DE 101 38 217.0. Therein, information packets are transmitted between a base station and a transponder. The information packets consist of a header section and a middle section with a data region. In the middle section, the data of the data region are encoded with the identifications allocated to the logic values of the information symbols in the header section. With different identifications of successive information packets, the data transmission rate can be adjusted. A disadvantage of the method is that disturbing or noisy interferences reduce the reliability of the data transmission in the communication due to reflections and/or absorptions when utilized in the range of UHF and higher frequencies. For the correction of the read errors, the entire data packet must be transmitted.
A further method for the transmission of data is represented in the publication DE 101 21 855.9. Therein, the modulation voltage is switched or alternated between two values with each new bit in the bit sequence of the data word, independent of the logic values of the data bits. Thereby, the phase position or phase angle is changed in a phase modulated carrier wave.
A further method is known from the publication EP 473,569 B1. Therein, digital data are exchanged between a base station and a passive transponder by means of an amplitude modulated carrier wave. The individual bits of a data word consist of a time span or interval in which the electromagnetic field is switched on and a time span or interval in which the electromagnetic field (field gap or notch) is switched off, whereby the field gap serves as a separator between two successive bits. The logic value of the bits is determined by the length of the time in which the electromagnetic field is switched on. The fixed time amount of the field gap is summed or additionally counted for the total time for the representation of the individual bits. Furthermore, in the passive system, the energy for the transponder is acquired out of the carrier field by means of absorption modulation.